The ink isn't even dry on a tentative two-year budget agreement, but conservatives in Congress are already pouncing.

GOP leaders from both ends of the Capitol met privately with their rank-and-file Monday evening to outline the general contours of the emerging agreement between Congress and the White House. It would boost defense and domestic spending over the next two years, and lift the nation’s debt limit through March 2017 — thereby eliminating the twin threats of a government shutdown and a debt default until after the November 2016 elections.

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But conservative lawmakers, eager to keep the strict spending caps from a 2011 budget agreement intact, were very skeptical of the deal after they emerged from close-door briefings with their leaders on Monday night.

Asked about the tentative agreement after the briefing, Alabama Sen. Jeff Sessions replied: “My knees quiver at the sound.”

In an interview, Sessions expressed frustration that outgoing Speaker John Boehner was hammering out the deal just days before he plans to give up the gavel for good. “What does Boehner got to do with it?” said an exasperated Sessions, the former top Republican on the Senate Budget Committee. “I’m worried about how fast it’s moving. I see no reason for that. Based on what I know now, it appears the president got whatever he wanted.”

Still, GOP leaders are operating under the assumption that despite the grumblings from the right, they should be able to draw enough votes from the center to comfortably pass the legislation in both chambers.

The budget deal, which has not yet been finalized, would boost defense and domestic spending above sequestration levels by $50 billion in the first year and $30 billion in the second year. In each year, there would be an additional $16 billion spent using the Overseas Contingency Operations fund. It would also curtail a huge increase in Medicare premiums due to go into effect in January for some beneficiaries — a provision sought by House Minority Leader Nancy Pelosi (D-Calif.)

To pay for the increased spending, congressional negotiators dug into a combination of health care savings and smaller revenue-raisers. But even though the boost in spending would be paid for — a key part of the GOP leaders’ sales pitch — some conservative lawmakers signaled they still wouldn't support the plan.

“I have strong concerns given that we did a budget earlier this year [and] took $7 trillion out of the president’s budget over the next 10 years,” said Sen. David Perdue (R-Ga.) as he left the Monday night meeting. “These last-minute deals make me very nervous.”

Not only will the increased spending levels make for heartburn with conservatives, but many of the offsets touch on political hot buttons.

Those pay-fors include a repeal of a piece of Obamacare, according to congressional sources. It would repeal Obamacare’s requirement that large employers automatically enroll employees in their health plans. The Congressional Budget Office has estimated that a different bill to repeal that provision would save the federal government $7.9 billion over a decade.

The plan would also prevent a 20 percent across-the-board benefit cut to the Social Security Disability Insurance program, resulting in $168 billion in long-term savings. The tentative deal would also be paid for by extending the Medicare sequester that was approved in the Budget Control Act for another year and setting up additional cuts to hospitals.

The tentative agreement would also impose policy changes to disability insurance, tax compliance, crop insurance, spectrum and the Strategic Petroleum Reserve. Lawmakers and aides cautioned that the negotiations were not completed, and some details could change before details are made public — likely by later Monday night.

Indeed, conservatives across the country have been watching for months to see how GOP leaders handle the spending caps that many on the right view as a major victory. Many conservatives are likely to interpret the budget deal, even with some new spending paid for with cuts and new revenues, as a retreat from the blunt spending restrictions of the Budget Control Act that was enacted into law in 2011.

“The biggest disappointment, in our minds, about Republicans in the House and Senate this entire year has been their failure on the budget,” said Americans for Prosperity President Tim Phillips said earlier Monday, before details of the budget deal began to materialize. “Let’s stick to those caps. You said you would do that. Keep your word. I mean, you told the American people you would do that.”

The discontent over the preliminary fiscal agreement also extended to the House on Monday night, where Rep. Justin Amash (R-Mich.) focused his ire over how leadership was handling the budget process.

“We're not just here to take commands. We're really tired of the top-down, micromanagement where you have just a few people, or in this case just the speaker and his team, determining the outcome,” Amash said. “This is a fair reason to vote against the bill.”

But the emerging agreement will likely win support from defense hawks who had demanded more funding for the Pentagon and were willing to strike a budget agreement with Democrats to do so, even if that meant boosting domestic spending as well.

Senate Armed Services Committee Chairman John McCain (R-Ariz.) told reporters that the top-line figures presented to senators at their closed-door briefing fell about $5 billion short in fiscal 2016 of what he had wanted. Still, he said the plan was “salable.”

“I think that we could move forward with this,” McCain said. “It averts a shutdown. It puts any of these problems into two years from now and so I think it’s the best deal we can get.”

Overall, the sentiment among Republicans was “positive,” said Senate President Pro Tempore Orrin Hatch (R-Utah). But GOP leaders know that things are going to get uglier as the details come out and the party’s conservative wing to shred the budget deal.

“Looking at the information that we’ve gathered so far, I’m not necessarily in a position where I think that’s in the best interest of our country going forward,” Sen. Tim Scott (R-S.C.) told reporters. “It’s just hard to justify that we’re not figuring out how to clamp down on spending.”